1. Field of the Invention
The present invention relates to a structure of a flexible tube including an interlock pipe and a bellows tube.
2. Description of the Related Art
In an exhaust pipe of an engine or the like, a part of the exhaust pipe is sometimes configured by a flexible tube in order to improve easiness of layout, etc. FIG. 5 shows an example of such a flexible tube. A flexible tube 1A has an outer blade 3, which is placed on the outer peripheral side of a bellows tube 9 having a bellows portion 9c, and an interlock pipe 4, which is placed on the inner peripheral side of the bellows tube 9.
Each of straight portions 2a of the bellows tube 9, and corresponding one of end portions 3a of the outer blade 3 are placed with being overlaid on the outer peripheral face of the interlock pipe 4. A protector 5 is placed on the outer peripheral side of the end portion 3a of the outer blade 3. The protector 5, the straight portion 2a, and the end portion 3a are welded to the outer peripheral face of the interlock pipe 4.
The inner peripheral diameter of the bellows portion 9c of the bellows tube 9 is set to be larger than that of the straight portion 2a, so that a gap is formed between the bellows portion and the outer peripheral face of the interlock pipe 4. Even when the flexible tube 1A swings due to vibrations of the engine or the like, therefore, the outer peripheral face of the interlock pipe 4 and the bellows portion 9c are prevented from contacting with each other.
In a flexible tube 1B which is structured as described above and has a long total length as shown in FIG. 6, when the flexible tube 1B vibrates, the swing amplitude of the interlock pipe 4 is larger as the length is larger. As a result, the outer peripheral face of the interlock pipe 4 and the bellows portion 9c contact with each other, thereby causing troubles such as noises.